Determination of gallium at trace levels using a spectrofluorimetric method in synthetic U-Ga and Ga-As solutions

Article abstract of DOI:10.1016/j.saa.2009.10.041

A simple, easy to use and selective spectrofluorimetric method for the determination of trace levels of gallium has been developed. A new Schiff base, N-o-vanillidine-2-amino-p-cresol (OVAC) was synthesized and its fluorescence activity with gallium investigated. Based on this chelation reaction, a spectrofluorimetric method has been developed for the determination of gallium in synthetically prepared Ga-U and Ga-As samples buffered at pH 4.0 using acetic acid-sodium acetate. The chelation reaction between Ga(III) and N-o-vanillidine-2-amino-p-cresol was very fast, requiring only 30 min at room temperature to complex completely. The limit of detection (LOD) (3σ) for Ga(III) was 7.17 nM (0.50 μg L^-1), determined from the analysis of 11 different solutions of 20 μg L^-1 Ga(III).

Full text of DOI:10.1016/j.saa.2009.10.041

Spectrochimica Acta Part A 75 (2010) 361–365
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Determination of gallium at trace levels using a spectrofluorimetric method in
synthetic U–Ga and Ga–As solutions
Derya Karaa,∗, Andrew Fisherb, Mike Foulkesb, Steve J. Hillb
a Department of Chemistry, Art and Science Faculty, Balikesir University, 10100 Balikesir, Turkey
b School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
A simple, easy to use and selective spectrofluorimetric method for the determination of trace levels of gal-
lium has been developed. A new Schiff base, N-o-vanillidine-2-amino-p-cresol (OVAC) was synthesized
and its fluorescence activity with gallium investigated. Based on this chelation reaction, a spectrofluo-
rimetric method has been developed for the determination of gallium in synthetically prepared Ga–U
and Ga–As samples buffered at pH 4.0 using acetic acid–sodium acetate. The chelation reaction between
Ga(III) and N-o-vanillidine-2-amino-p-cresol was very fast, requiring only 30 min at room temperature to
complex completely. The limit of detection (LOD) (3ꢀ) for Ga(III) was 7.17 nM (0.50 ␮g L−1), determined
from the analysis of 11 different solutions of 20 ␮g L−1 Ga(III).
Received 17 February 2009
Received in revised form 17 October 2009
Accepted 26 October 2009
Keywords:
Gallium
N-o-vanillidine-2-amino-p-cresol
Spectrofluorimetry
© 2009 Elsevier B.V. All rights reserved.
1. Introduction
been used to determine gallium. The last three methods involve
the use of expensive and sophisticated instrumentation. Sensitive
Sensitive and reliable methods for the determination of trace
concentrations of gallium are very important in different fields.
Alloys and compounds of gallium have been used in electronic and
optical devices and also in medical applications. Gallium arsenide
(GaAs) is an important semiconductor and is used to make devices
such as microwave frequency integrated circuits (i.e. MMICs),
infrared light-emitting diodes, laser diodes and solar cells [1]. Gen-
erally, between 2 and 90% gallium is added to uranium to make
U–Ga alloys. Uranium is not stabilized in normal atmospheric
conditions and the addition of gallium stabilizes it [1]. Physical
properties of semiconductor materials greatly depend upon the sto-
ichiometric composition as well as on the level of trace impurities
present. Accurate and precise determination of gallium content is,
therefore, an essential requirement in compound semiconductor
materials such as Ga–As and Ga–U alloys and also in standard ref-
erence materials of Pu–Ga alloy for chemical characterization of
nuclear fuels. In addition, since the usage of gallium is increasing,
methods capable of its determination in environmental samples
also need to be developed so that monitoring of contamination may
occur.
determination of gallium can also be achieved by using fluori-
metric methods [12–15], but extraction steps are often required
to separate it from other ions that interfere during the analysis.
Molecular fluorescence spectroscopy is an increasingly important
analytical technique since it is sensitive (with limits of detection
in the range 10−6 to 10−9 M) and can be selective. In addi-
tion, it also offers good precision and accuracy whilst retaining
a very long linear calibration range that often covers several
orders of magnitude. It therefore possesses some advantages
when compared with other instrumental methods. 2,4-[Bis-(2,4-
dihydroxybenzylidene)]-dihydrazinoquinazoline (DBHQ) with two
Schiff base moieties has also been reported as a fluorescent chelat-
ing ligand for gallium ions [16]. This work yielded a relatively low
LOD of 3.5 ng mL−1, which is better than flame atomic absorption
and ICP-OES, but is inferior to that obtained using ICP-MS. In addi-
tion, the method was also found to suffer from interferences from
aluminium and from the transition metals ions Fe3+, Cu2+ and Co2+
although these interferences could be overcome by the addition of
fluoride ions.
In this work, a new simple and sensitive fluorimetric method for
the determination of gallium is reported using a new Schiff base
compound, N-o-vanillidine-2-amino-p-cresol (OVAC) as a com-
plexing agent. The method does not require any extraction step
and is applied in a 50% water and acetone mixture. Multiple lin-
ear regression may be applied to the determination of gallium in
the presence of aluminium. This method is usually suitable for the
interpretation of very similar spectra of the particular components,
and enables multiple components of a mixture to be determined
Various analytical methods such as voltammetry [2,3] atomic
absorption spectrometry [4,5], inductively coupled plasma atomic
emission spectrometry [6,7], inductively coupled plasma mass
spectrometry [8,9] and neutron activation analysis [10,11] have
∗
Corresponding author.
E-mail address: dkara@balikesir.edu.tr (D. Kara).
1386-1425/$ – see front matter © 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2009.10.041

362
D. Kara et al. / Spectrochimica Acta Part A 75 (2010) 361–365
simultaneously. The developed method has been applied to syn-
thetic Ga–As and Ga–U samples.
2. Experimental
2.1. Apparatus
Fluorescence measurements were made using a Hitachi 4500
fluorescence spectrophotometer (Wokingham, UK) using a slit-
width of 5.0 nm for both excitation and emission. The excitation
and emission wavelengths were set to 442.0 and 559.0 nm, respec-
tively. Adjustments to the pH of the solutions were monitored using
a Jenway 3305 pH meter.
2.2. Reagents and solutions
Fig. 1. The excitation (a) and emission (b) spectra of the Ga(III)–OVAC complex pre-
pared using 50 ␮g L−1 Ga(III) and 2.5 × 10−4 M OVAC. Also shown are the excitation
(c) and emission (d) spectra of 2.5 × 10−4 M OVAC at pH 4.0.
The stock solution containing 10 mg L−1 of Ga was prepared
from 995 mg L−1 stock standard solutions (Aldrich, Dorset, UK).
The stock solutions containing U, As and Al were prepared from
10 000 mg L−1 stock standard solutions (BDH, Aristar, Poole, UK).
Working standards of between 2.5 and 20 ␮g L−1 were prepared on
a daily basis by dilution from a 1 mg L−1 solution prepared from this
stock standard. Buffer solutions, at a concentration of 1.0 M and at
pH 4.0, were prepared using pure acetic acid and sodium acetate
(ARISTAR, BDH).
Doubly de-ionized water (18.2 Mꢁ cm) obtained from a Maxima
water system (Elga, Buckinghamshire, UK) was used throughout.
Nitric acid (ARISTAR) was purchased from BDH. o-Vanilline (98.5%
Fluka), 2-amino-p-cresol (97% Aldrich) and acetone (99.0% Fluka)
were also used.
has excitation and emissions wavelengths of 350 and 450 nm,
respectively. The standard solutions that gave absorbance values
of between 0.01 and 0.1 at the excitation wavelength were pre-
pared for the Ga–OVAC complex and quinine sulfate separately.
The absorbance values were recorded for these solutions at 442 nm
for Ga–OVAC complex and at 350 nm for quinine sulfate standard
solutions. The emission values for these solutions were recorded at
559 nm for the Ga–OVAC complex and at 450 nm for quinine sulfate.
The absorbance values were plotted against fluorescence values for
both the Ga–OVAC complex and the quinine sulfate. The gradients
of these graphs were used to calculate the fluorescence quantum
yield of the Ga–OVAC complex.
2.3. Synthesis of N-o-vanillidine-2-amino-p-cresol (OVAC)
3. Results and discussion
N-o-vanillidine-2-amino-p-cresol (OVAC) was synthesized
according to the procedure given in the literature [17]. OVAC was
prepared by refluxing one equivalent of o-vanilline (40 mmol) with
one equivalent (40 mmol) of 2-amino-p-cresol in 100 ml of ethanol
for 4 h. The solution turned red and, on cooling, the orange-red
Schiff base solid appeared. The Ethanol was removed by rotary
evaporation and the solid purified by re-crystallization from hot
ethanol. Characterization of the ligand was reported previously
[18].
3.1. Fluorescence spectrum of the Ga–OVAC complex
In order to determine the optimum analytical wavelengths, the
spectral characteristics of the Ga(III)–OVAC complex was studied
at various pH values. The excitation and emission spectra of the
Ga(III)–OVAC complex indicated that the most intense excitation
and emission wavelengths were at 442.0 and 559.0 nm, respec-
tively. The un-complexed ligand OVAC gave very low intensity at
these wavelengths. Fig. 1 shows the excitation and emission spectra
for both the Ga(III)–OVAC complex and the OVAC ligand prepared
using the same conditions of pH 4.0 and an acetone concentration
of 50%.
2.4. Procedures
Sufficient Ga solution was added to pre-cleaned 10 mL vol-
umetric flasks to produce calibration standards in the range
2.5–20 ␮g L−1. Then, 1 mL of acetate buffer (1.0 M, pH 4.0) and
5.0 mL of 1.0 × 10−4 M OVAC prepared in acetone were added
before the solution was diluted to volume using ultra-pure water.
The solution was mixed and equilibrated at room temperature for
30 min, and then the fluorescent intensity was measured under
optimal excitation and emission wavelengths using a 1 cm quartz
cell. The gallium concentrations in the synthetic Ga–As and Ga–U
samples were determined from these calibration graphs. The deter-
mination of gallium in the presence of aluminium was achieved
using a multiple linear regression method. The calibration set
was performed using three different concentrations (40, 60 and
80 ␮g L−1) of Ga and Al.
3.2. Effect of pH
The pH of the solution had a great influence on the fluorescence
intensity of the Ga(III)–OVAC complex. The pH of the solutions was
adjusted using dilute HCl and/or NaOH to values between 2.0 and
10.0 (Fig. 2). The experimental results showed that the highest
fluorescence intensity signals were observed at a pH of between
approximately 3.5 and 5.0. Therefore, a pH fixed at 4.0 by an acetate
buffer was used as optimum for all subsequent work.
3.3. Effect of solvent and solvent ratio
The use of an organic solvent was necessary because the ligand
(OVAC) is not soluble in water. Therefore solvents such as ethanol,
acetone, methanol and DMF were tested in an attempt to increase
the fluorescence intensity for the Ga(III)–OVAC complex. Acetone
and ethanol were found to be the most suitable for this purpose
because the use of DMF led to a substantially lower fluorescent
intensity. Subsequently, acetone was selected as the solvent for
2.5. Determination of fluorescence quantum yield of the
Ga–OVAC complex
Fluorescence quantum yield of the Ga–OVAC complex was
determined using the comparative method described by Williams
et al. [19]. Quinine sulfate was used as a reference standard which

D. Kara et al. / Spectrochimica Acta Part A 75 (2010) 361–365
363
Table 1
Effect of potentially interfering ions on the fluorimetric determination of gallium
(5 ␮g L−1) (tolerable error 5%).
Concentration (␮g L−1
)
Potential interference
5000
Hg2+, Ni2+, Zn2+, Mg2+, Pb2+, Cd2+, Ca2+, Co2+
,
2−
Ba2+, Mn2+, Sr2+, Na+, K+, B4O72−, S2O3
,
CO32−, NO3−, HCO3−, CH3COO−, SO42−, I−, Cl−
,
Br−, SO32−, NO2 −, As and U
Cr3+
1000
2500
250
5
2−
2−
CrO42−, Cr2O72−, HPO4 and H2PO4
Fe3+, Fe2+, Sn2+ and Cu2+
F− and Al3+
to identify the complex stoichiometry. In order to determine the
stoichiometry of the OVAC–Ga complex, the continuous variations
method was adopted to the optimized spectrofluorimetric method.
In the continuous variations method, the concentration of gallium
and OVAC are varied so that their sum is equal to 1 × 10−5 M.
The pH was kept constant at a value of 4.0 by an acetate buffer
solution. The fluorescence intensities of these solutions using exci-
tation at 442 nm and emission at 559 nm were plotted against the
concentration ratio of gallium to the sum of Ga and OVAC. The max-
imum fluorescence intensity value corresponds to a molar ratio
[Ga3+]/[OVAC] of 1/2 which supports a GaL2 stoichiometry.
Fig. 2. The effect of pH on fluorescence intensity of the Ga(III)–OVAC complex
(50 ␮g L−1 Ga(III) and 2.5 × 10−4 M OVAC).
further work. Different acetone–water ratios were investigated by
changing the percentage of acetone between 20 and 85%. As the
percentage of acetone increased, the fluorescence intensity also
increased. However, a 50% acetone concentration was selected as
an optimum solvent mixture because in systems containing a high
percentage of water, hydrolysis of the Schiff base occurred. Con-
versely, an extremely high percentage of acetone was not selected
since, to be useful analytically, buffer and Ga(III) also have to be
added. Once these were added the acetone concentration could not
exceed 50%. A 50% acetone concentration was therefore selected
as a compromise between greatest sensitivity and the ability to
introduce all the relevant reagents/sample.
3.7. Effect of potential interferences
A systematic study of the potential interferences arising through
the presence of other ions during the determination of Ga(III) was
carried out using 10 mL solutions containing 5 ␮g L−1 Ga(III) and
various amounts of foreign ions as described in the procedure. The
results are shown in Table 1.
The most interfering ions during the determination of Ga in
water samples are aluminium and fluoride. The interference of flu-
oride arises because Ga can form a series of stable compounds with
F−, e.g. GaFx(x−3)−, where x = 1–5, and once the Ga is combined with
fluoride it may not necessarily be available to become complexed
with the Schiff base ligand. The interference of F− on the determina-
tion of Ga can be removed with the addition of 100 ␮L of 100 mg L−1
Be2+. The Be2+ reacts rapidly to combine with F− in preference to the
Ga and the beryllium fluoride molecules formed effectively release
the Ga so that it may be determined fluorimetrically. The blank level
of the Be2+ solution is negligible, and therefore did not affect the
determination of Ga during routine analysis.
3.4. Effect of time and complex stability
The kinetics of the formation of Ga(III)–OVAC complex were
investigated by measuring the fluorescence intensity of the com-
plex solution containing 1 mg L−1 Ga(III) and 2.4 × 10−4 M OVAC.
The fluorescence intensity was measured over a time period of
between 5 min and up to 1 day. The results indicated that a time
of 30 min was sufficient for complete complexation, even at room
temperature. In addition, the fluorescence intensity did not change
over a 24 h period, demonstrating that the gallium forms a stable
complex with the OVAC.
The other most interfering ion is aluminium. Ga–As and Ga–U
alloys can become contaminated with aluminium via dust. OVAC
has previously been used for the development of a fluorescence
method for the determination of aluminium by our research group
[18,20]. Fig. 3 shows that the fluorescence spectra of Al and Ga
with OVAC are very similar and overlapped. In addition, the flu-
orescence signal of the Al–OVAC complex is higher than that of
Ga–OVAC at all wavelengths. A multiple linear regression method
was therefore employed for the determination of gallium in the
presence of aluminium. A set of 9 solutions containing three dif-
ferent concentrations of Al and Ga (40, 60 and 80 ␮g L−1) were
prepared (Table 2) and the fluorescence intensities were measured
at 2 wavelengths (500 and 560 nm) since these wavelengths have
higher fluorescence intensities for both Al and Ga. The linear regres-
sion equations that were produced at the 2 wavelengths using the
Statistica chemometric package [21] are given below. In these equa-
tions, y1 and y2 are the measured fluorescence intensities at the two
wavelengths:
3.5. Concentration of OVAC
Optimization of the concentration of OVAC required for com-
plete complexation of Ga in solution is very important when
developing a method for the determination of gallium because
it enables maximum sensitivity, accuracy and precision to be
obtained. Fig. 1 shows that the un-complexed OVAC ligand yields
a very low fluorescence signal compared with the Ga complex, and
therefore a very low blank signal is obtained. A series of solu-
tions containing various concentrations of OVAC (0.25–500 ␮M)
and 1 ␮M of Ga were prepared to investigate the effect of the
amount of OVAC on the fluorescence intensity. Results indicated
that the fluorescence of the complex solution containing 1 ␮M of Ga
reached a maximum when the amount of OVAC exceeded 100 ␮M
at the optimized pH and time. Therefore 100 ␮M was used for all
subsequent work.
3.6. The stoichiometry of the Ga(III)–OVAC complex
y1 = 0.565CGa + 2.481CAl + 31.994 (500 nm)
y2 = 0.992CGa + 2.670CAl + 36.919 (560 nm)
Although the appropriate concentration of OVAC needed in the
Ga(III)–OVAC complex has been determined, it is also important

364
D. Kara et al. / Spectrochimica Acta Part A 75 (2010) 361–365
The other interfering ions are Fe(II), Fe(III), Cu(II) and Sn(II)
which give interfering effects at concentrations often far greater
than 250 ␮g L−1. Of these ions, Fe(II), Fe(III) and Cu(II) quench the
fluorescence signal whereas the presence of large concentrations
of Sn(II) increase the signal. If the concentration of Fe is high in the
samples, it may be complexed using ascorbate added to the solu-
tions at a final concentration of 4.10−5 M. Addition of the ascorbate
was found to decrease the interference from iron to a level that
could be regarded as being insignificant.
3.8. Precision and detection limit
A calibration graph for the determination of Ga(III) was con-
structed under the optimum experimental conditions. The limit of
detection (LOD) (3ꢀ) for Ga(III) was 7.17 nM (0.50 ␮g L−1), deter-
mined from the analysis of 11 different solutions of 20 ␮g L−1
Ga(III).
The calibration for the method was linear up to at least
10000 ␮g L−1 and the regression equation was: Y = 1.82CGa + 0.135
(r = 0.997). A standard of 20 ␮g L−1 of Ga(III) prepared in ultra-pure
water was analyzed in replicate (n = 30) and the relative standard
deviation was calculated to be 0.87%.
Fig. 3. The fluorescence spectra of Al–OVAC and Ga–OVAC complexes at 442 nm
excitation wavelength.
The basic criterion for correctness of the results obtained by PLS
calculation is agreement of the actual (given) concentrations of
the individual components with the calculated (predicted) values
expressed by the following relations [22]:
3.9. Determination of Gallium in synthetic Ga–U and Ga–As
sample solutions
Different percent of Ga–As, Ga–U and Ga–As-U solutions given
in Table 3 were prepared using pure standard solutions of Ga, As
and U. Gallium concentrations in these samples has been deter-
mined using the proposed procedure without using any separation
or preconcentration steps. Table 3 shows that the relative errors of
determination of gallium in synthetic solutions are very small even
when it contains 90% of U and As. It also shows that the accuracy
and precision of the developed method is acceptable.
Component relative prediction error (CRPE)
ꢀ
ꢃ
ꢁ
ꢁ
ꢂ
T
i=1
(cij − c∗)2
i=1ci2j
ij
CRPEj =
× 100
ꢃ
T
Sample relative prediction error (SRPE)
ꢀ
ꢁ
ꢁ
ꢂ
ꢃ
M
(cij − c∗)2
j=1ci2j
3.10. Determination of fluorescence quantum yield of the
Ga–OVAC complex
j=1
ij
SRPEi =
× 100
ꢃ
M
The relative quantum yield is generally determined by com-
paring the wavelength-integrated intensity of an unknown sample
to that of a standard [19,23]. The most accurate method to deter-
mine quantum yields is to prepare solutions with optical densities
between 0.1 and 0.01, and then to calculate the quantum yield using
the gradients determined for the sample and the reference. In this
case quantum yield can be calculated using:
where T is sample number, M is the number of components and
cij and c∗ are the actual and calculated concentration values of the
ij
particular components.
Table 2 shows the actual concentrations and the calculated (pre-
dicted) concentrations from these two equations of Al and Ga,
percent relative errors of determination and percent sample rel-
ative prediction errors [22]. In addition, the percent component
relative prediction errors [22] are 5.11 and 6.00 for Ga and Al,
respectively. These results show that the gallium concentration can
be calculated very accurately using the two equations and the fluo-
rescence intensities measured for an Al and Ga mixture at 500 and
560 nm.
ꢆ
ꢄ
ꢅ
Grad
n2
nR2
Q = QR
GradR
where Q is the quantum yield, Grad is the gradient obtained from
the plot of the fluorescence intensity vs. absorbance values and
Table 2
Concentrations of Al and Ga in standard solutions.
Gallium
Aluminium
SRPEb (%)
Sample number
Actual (␮g L−1
)
Predicted (␮g L−1
)
REa (%)
Actual (␮g L−1
)
Predicted (␮g L−1
)
REa (%)
1
2
3
4
5
6
7
8
9
80
80
80
60
60
60
40
40
40
79.16 2.17
80.80 5.24
80.00 4.96
60.98 1.90
60.50 3.44
61.15 2.09
42.37 1.43
38.90 2.60
39.81 3.38
−1.1
1.0
0
1.6
0.8
80
60
40
80
40
60
80
40
60
82.81 5.66
63.08 2.30
40.36 0.81
77.61 4.60
41.39 3.37
62.18 1.51
77.54 5.31
41.64 1.46
62.61 1.04
3.5
5.1
0.9
5.7
5.9
5.3
5.4
5.3
4.1
7.0
6.1
4.8
−3.0
1.2
1.9
5.9
3.7
−3.1
−2.8
0.7
−0.5
4.4
a
Percent relative error.
Percent sample relative prediction error.
b

D. Kara et al. / Spectrochimica Acta Part A 75 (2010) 361–365
365
Table 3
Determination of gallium in the synthetic Ga–U and Ga–As samples.
% Ga
% U
% As
Added Ga (mg L−1
)
Added U (mg L−1
)
Added As (mg L−1
)
Found Ga (mg L−1
)
RE (%)
100
50
0
50
0
–
–
–
–
–
–
50
66.7
71.4
80
83.34
90.91
50
66.67
16.67
46.67
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
–
2
4
5
8
10
20
–
–
–
–
–
–
4
2
8
6
–
–
–
–
–
–
–
2
4
5
8
10
20
6
8
2
7
1.989 0.004
2.010 0.003
1.990 0.021
1.991 0.001
1.992 0.006
1.964 0.010
2.023 0.011
1.967 0.004
2.000 0.004
1.983 0.010
2.018 0.004
1.995 0.005
2.011 0.009
1.995 0.015
1.997 0.010
1.992 0.020
1.991 0.015
−0.55
0.50
33.3
28.6
20
16.66
9.09
50
33.3
28.6
20
16.66
9.09
16.66
16.67
16.67
13.33
66.7
71.4
80
83.34
90.91
–
–
–
–
–
−0.50
−0.45
−0.40
−1.80
1.15
−1.65
0
−0.85
0.90
−0.25
–
0.55
33.3
16.67
66.67
40
−0.25
−0.15
−0.40
−0.45
n is the refractive index. The subscript R refers to the reference
fluorophore of known quantum yield. In this study, the reference
compound used was quinine sulfate.
thetic samples could be determined with this new method with
very good precision and accuracy. This method does not require
any separation or preconcentration steps. The interference from F−
could be removed by adding Be to the solution. Al interference can
be eliminated by using multiple linear regression analysis since the
spectra of both Al and Ga OVAC complexes are overlapped. Multi-
ple linear regression analysis is a very simple method requiring
only the preparation of a mixture of solutions of different concen-
tration of Al and Ga. Both gallium and aluminium concentrations
can be determined simultaneously using multiple linear regression
analysis.
The reference fluorescence quantum yield for quinine sulfate
in 0.1 M H2SO4 was given as 58% at an excitation wavelength of
350 nm [24]. Gradient values were found to be 2470 and 78 000
for the Ga–OVAC complex and quinine sulfate, respectively. The
refractive indexes were taken to be 1.33 and 1.35879 [25] for water
and 50% acetone–water mixtures. The fluorescence quantum yield
was calculated to be approximately 2% for the Ga–OVAC complex in
the experimental conditions at pH 4.0 and in a 50% acetone–water
mixture.
References
3.11. Comparison with other analytical techniques
[1] http://en.wikipedia.org/wiki/GaAs.
[2] T.K. Bhardwaj, H.S. Sharma, S.K. Aggarwal, J. Nucl. Mater. 360 (3) (2007)
215–221.
[3] H.S. Sharma, T.K. Bhardwaj, P.C. Jain, S.K. Aggarwal, Talanta 71 (3) (2007)
1263–1267.
[4] J.C. Yu, C.M. Wai, Anal. Chem. 56 (1984) 1689–1691.
[5] Y. Hayashibe, M. Kurosaki, F. Takekawa, R. Kuroda, Mikrochim. Acta 98 (4–6)
(1989) 163–171.
[6] B. Gong, X. Li, F. Wang, X. Chang, Talanta 52 (2000) 217–223.
[7] H. Imura, A. Oshiro, K. Ohashi, Anal. Sci. 14 (1998) 1093–1098.
[8] K.J. Orians, E.A. Boyle, Anal. Chim. Acta 282 (1993) 63–74.
[9] Q. Liang, H. Jing, D.C. Gregoire, Talanta 51 (2000) 507–513.
[10] K. Nakamura, M. Fujimori, H. Tsuchiya, H. Orii, Anal. Chim. Acta 138 (1982)
129–136.
[11] E.L. Lakomaa, P. Manninen, R.J. Rosenberg, R. Zilliacus, J. Radioanal. Nucl. Chem.
168 (1993) 357–366.
[12] F.D. Snell, Photometric and Fluorimetric Methods of Analysis. Part I, Wiley, New
York, 1978, pp. 497–534.
[13] A.I. Busev, V.G. Tipsova, V.M. Ivanov, Analytical Chemistry of Rare Elements,
Mir, Moscow, 1981, pp. 276–290.
[14] A. Fernández Gutiérrez, A. Mun˜oz de la Pen˜a, Molecular Luminescence Spec-
The method developed in this study yielded low limits of detec-
tion, had a long linear calibration range and was relatively free
from interferences. Those interferences that did exist could easily
be overcome. For some “interferences”, notably aluminium, mul-
tiple linear regression could be used. This effectively turned the
procedure into one that was capable of the simultaneous determi-
nation of Al and Ga. Other procedures described in the literature
have also claimed low limits of detection [2] but have experienced
some problems. The method developed by Bhardwaj et al. was not
suitable if the gallium in the sample was present at less than 2%
(m/m) since interference from uranium was found to prevent the
proper deposition of gallium on the electrode [2]. The most simi-
lar publication found in the literature to the work described here
was produced by Kimura et al. [16]. As discussed in the introduc-
tion, their work suffered from similar interferences, but yielded an
inferior LOD of 3.5 ng mL−1; a factor of 7 worse than the method
proposed in this work. In addition, Kimura et al. used fluoride
ions to overcome interferences, whereas in the work presented
here, the presence of fluoride could act as interference since it
caused problems with the simultaneous determination of the gal-
lium and aluminium. The simultaneous nature of the determination
is another of the advantages offered in this work.
troscopy, Wiley, New York, 1985.
[15] G.G. Guilbault, Practical Fluorescence, Marcel-Dekker, New York, 1990.
[16] J. Kimura, H. Yamada, H. Ogura, T. Yajima, T. Fukushima, Anal. Chim. Acta 635
(2009) 207–213.
[17] M. Cindric, N. Strukan, V. Vrdoljak, B. Kamenar, Z. Anorg. Allg. Chem. 630 (4)
(2004) 585–590.
[18] D. Kara, A. Fisher, S.J. Hill, J. Environ. Monit. 9 (2007) 994–1000.
[19] A.T.R. Williams, S.A. Winfield, J.N. Miller, Analyst 108 (1983) 1067–1071.
[20] D. Kara, A. Fisher, S.J. Hill, Anal. Chim. Acta 611 (2008) 62–67.
[21] Statistica 99 edition (1984–1999), Kernel release 5.5, StatSoft Inc.
ˇ
[22] S. Vojta, L. Jancˇárˇ, L. Sommer, J. Fluoresc. 18 (2) (2008) 339–347.
4. Conclusion
[23] http://www.iss.com/resources/tech3/.
[24] J.R. Lakowicz, Principles of Fluorescence Spectroscopy, 2nd ed., Kluwer
Academic/Plenum Publishers, New York, London, Moscow, Dordrecht,
1999.
A spectrofluorimetric determination method has been devel-
oped for the determination of gallium in U–Ga and U–As alloys.
Gallium percentage between 9 and 50% for the U–Ga and U–As syn-
[25] M. Iglesias, B. Orge, J. Tojo, Fluid Phase Equilib. 126 (1996) 203–223.